I found a small white mark on my watch case and strap. I have no clue where it came from and I am unable to clean it off. You really can't see the mark if you are looking straight down at it, but when looking at it from an angle it becomes visible. I am generally very careful with my watches, and do not know how it could have gotten there. Has anyone else experienced a mark like this on a resin band? If so, any tips for removing it? Thanks.